Image registration is a process of transforming different images into a common coordinate space. Image registration may denote reconstruction of at least two images into a single synthesized image. A user may ascertain the correspondence between different images, according to image registration.
In the field of diagnosis based on medical images, image registration is widely used in order to compare images of a diseased body part with each other according to time, to compare images of a diseased body part with each other according to modalities of medical imaging and to compare an image of a diseased body part with an image of normal tissue. In diagnosis, in order to use an image, which is obtained by increasing strengths of or remedying weaknesses of different image acquisition modalities, image registration is used in which acquired images are represented in a same space to facilitate comparison therebetween.
For example, when a lung or a stomach is filled with air, an ultrasonic diagnosis device, a computed tomography (CT) diagnosis device, and a magnetic resonance imaging (MRI) diagnosis device have difficulty in diagnosing a lesion when only medical images of the lung or stomach are viewed. There is therefore need for an image registration system capable of performing image registration between a medical image provided by a photographing device inserted into a region of interest of a target object and a medical image provided by an ultrasonic diagnosis device, a CT diagnosis device, or an MRI diagnosis device.
In addition, an ultrasound imaging system has noninvasive and nondestructive characteristics and is thus widely used in the medical field to obtain information about the inside of a target object. Since an ultrasound imaging system is capable of providing a high-resolution image of the inside of a target object to doctors in real time without having to perform a surgical operation of making an incision in the target object and observing it, the ultrasound imaging system is widely used in the medical field. However, since an ultrasonic image has a low signal-to-noise ratio, an image registration system for performing image registration between an image acquired using any of other medical image acquisition methods, such as a CT image, and an ultrasonic image is needed to address this problem.
An image registration method and apparatus capable of quickly providing an accurately registered image is needed by a user to accurately diagnose a disease by using a registered image.